1. Field of the Invention
The present invention relates to an apparatus for determining the concentration of oil in another liquid, which apparatus is especially useful for measuring the concentration of oil contained in industrial waste water anc river water.
2. Description of the Prior Art
An apparatus for determining the concentration of oil contained in various kinds of water is known from U.S. Pat. No. 4,103,162. It comprises an extraction apparatus for introducing into an extractor a sample of an oil-containing water and an amount of an oil-extracting solvent by means of a pump. The separator separates the liquid mixture in said extractor into said solvent and the sample water, and an analyzer is used for analyzing the separated solvent containing oil therein to determine the concentration of oil.
Such an apparatus for determining the concentration has disadvantages which have a bad influence upon the measurement. For example, oils and oily suspensions, such as plankton, contained in the sample of water to be measured adhere to portions of the pump for introducing the sample of water into the extraction apparatus which portions are contacted by the liquids. In the case of a diaphragm pump, these portions are the diaphragm, check valve and the like where the flowing speed is suddenly changed. This has an influence upon the stability of the pump during discharge, and accumulations sometimes come off and produce noises.